The present invention relates to a method of reducing the staining caused by dentifrice compositions containing stannous. The present inventors have discovered that the use of a polyphosphate will help to reduce the staining that is associated with stannous. It has also been discovered that certain polyphosphates, in particular, linear polyphosphates with average chain lengths of about 4 or more will reduce the staining of the stannous without reducing the efficacy of the stannous.
The term “stannous” as used herein, is defined to mean the stannous that is in a dentifrice. It may refer to the stannous ions that are provided by a stannous salt. Stannous salts which contain stannous ions are commonly known. Stannous has been found to provide antigingivitis and antiplaque benefits. In addition stannous may also help to improve breath and reduce sensitivity. Dentifrices containing stannous are also known to be astringent and to cause staining on a subject's tooth surface. Some previous attempts to reduce the staining of stannous have been successful. However, once the staining was reduced, the efficacy of the stannous was also significantly reduced. For example, when a pyrophosphate, diphosphonate (AHP), and tripolyphosphate are used in a dentifrice with stannous, the efficacy of the stannous is reduced. This reduction in efficacy occurs even if the stannous is in a separate phase from the pyrophosphate, diphosphonate, and tripolyphosphate. One having ordinary skill in the art would assume that a polyphosphate having an average chain length of about 4 or more would behave similarly to the pyrophosphate. The present inventors have found that an unexpected result occurs with the polyphosphate as it reduces the staining but does not significantly reduce the efficacy of the stannous.
To improve consumer acceptance and compliance with the use of dentifrices containing stannous, a method is needed to reduce the amount of staining that occurs on a subjects teeth while still maintaining the efficacy of the stannous.
Therefore, it is an object of the present invention to provide a method of reducing staining of dentifrice composition containing stannous by administering to a subject a stable dentifrice compositions comprising two dentifrice compositions which are contained in physically separated compartments, allowing maximum fluoride and polyphosphate delivery to the oral cavity. The first dentifrice composition comprises a polyphosphate and has a limited total water content while the second composition comprises stannous ions. It is also an object of the present invention to provide a method of reducing staining of dentifrice composition containing stannous by administering to a subject a stable single phase dentifrice composition. The composition will comprise a polyphosphate, a stannous ion delivered from a source other than stannous fluoride, and have a limited total water content.
These and other objects of the present invention will become readily apparent from the detailed description which follows.
All percentages used herein are by weight of the dentifrice composition, unless otherwise specified. The ratios used herein are molar ratios of the overall composition, unless otherwise specified. All measurements are made at 25° C., unless otherwise specified.